The invention relates to a self-cleaning reactor/mixer, in particular a disk reactor, with a large available useful capacity, which cleans itself kinematically, comprising at least two or more parallel shafts rotating in the same direction, on which axially offset, not necessarily circular disks with scrapers distributed on their circumference are situated, and a surrounding housing.
The mixer is used in process engineering to process fluids and cohesive bulk materials. The mixer is extensively self-cleaning kinematically and has a large available useful capacity.
In process engineering, when producing and processing i.a. plastic materials and rubber, it is necessary to treat highly viscous fluids. In particular, apparatuses are required for mixing, evaporation and reaction purposes. Said apparatuses have to enable a good mixing action and, in the case of evaporation, also enable rapid renewal of the free surfaces.
Product deposits on the walls of such mixers, e.g. in the case of polymerization reactions, may lead to impairment of the process. Undesired side reactions are encouraged in the deposits on account of the substantially prolonged retention time. This leads to contamination of the product. Product deposits on the walls may be avoided by kinematic self-cleaning of the mixer.
To minimize apparatus costs, there should be the largest possible capacity available for the material to be mixed.
A known solution to the described problem is possible with the aid of multi-axis disk reactors. The basic construction of such a reactor is described i.a. in the specification FR-A-1 197 720.
European application EP 0 460 466 A1 describes how-the scrapers of a disk reactor may be designed for rotation in opposite directions or in the same direction in order to achieve kinematic cleaning of the scrapers and extensive cleaning of the complete reactor.
DE-OS 41 26 425 A1 describes a reactor with contrarotating shafts, which is completely kinematically self-cleaning.
In JP-A-63 232 828, a reactor rotating in the same direction is illustrated as an example, which is completely self-cleaning but limited to an available useful capacity of less than 62%.
What all of the three above-mentioned mixers have in common is that, during scraping of the housing wall, there is a product-side angle (see also FIG. 8) of less than 60.degree. between the housing wall and the scraper surface. Such mixers are however not very suitable or totally unsuitable for mixing solids-bearing and extremely viscous materials since the material to be mixed or the solid rapidly becomes compacted and compressed between the housing wall and the scrapers, causing subsequent blocking of the rotor.